Ideas on a random no-start condition?

[dnguyen1963]

It is always a good idea to tee in a pressure gauge in the fuel line going into the fuel rail when troubleshooting fuel related problems. You can monitor the pressure during running and dying. If the pump whines then it is on its way out. Check the pump sock for particles. It could be completely clogged.

[LateFan]

Fuel pumps are often intermittent when they fail. Kinda miss mechanical fuel pumps that would leak when they went bad, similar to a water pump.
Sounds like you need at least one fuel pump. If it was for my kid, I would replace them both and a new filter. Would hate for him to get stranded in some strange place.
The rising idle is more than likely your ICV. You can ruin them by cleaning them. The best test is if they are working right.
You can drill a quarter inch hole in a penny. Pull the air meter side of the hose at the ICV. Put the penny there and re connect. It should idle at about 600rpm.
Good until you buy a new one.

I agree - the idea of this car is so he can take it on trips alone with minimal tools and trust it.

Pumps are probably next. I may do the Chevy Vega in-tank thing for budget.

I did clean the ICV - I thought that was a good thing (?). It rattles when shaken. It hums when running. It passed the multimeter tests. When I unplug it while running the engine shoots up, then nearly dies, catches itself at 800 or so, races again. With it plugged in, there is a little bit of cycling when fully warm.

I've heard about the penny thing. You're putting it on the hose to the intake boot (this is an '86 E), or on the hose to the cold start valve on the intake?

[LateFan]

It is always a good idea to tee in a pressure gauge in the fuel line going into the fuel rail when troubleshooting fuel related problems. You can monitor the pressure during running and dying. If the pump whines then it is on its way out. Check the pump sock for particles. It could be completely clogged.

I've read that here. Part of me is thinking, just put that pressure gauge money toward new pumps.

This car sat for a while, so clogged pick-up is a possibility.

[LateFan]

New in-tank Airtex fuel pump this weekend. Starts (barely), barely idles, sputtering black smoke, won't stay running...

Inside of tank looked very clean. Only a tiny bit of grit on the pickup screen below the intake pipe.

Need to re-test cold start valve now that thermo-time switch was replaced. We may not be getting a cold-start squirt.

The coil showed higher numbers than the Bentley chart shows...like 1.5 ohms vs .5 in Bentley. Am I not getting enough spark? I'll re-check that tonight.

[dsphil]

Did you replace the main relay?

[LateFan]

Yes, we did - the main relay (white) and the fuel pump relay next to it.

My coil numbers are:

.9 to 1.2 ohms from + to - (it cycles up and down as far as .7 to 1.5)

5470 ohms from center post to +

Bentley says .5 ohms and 5000 ohms, and to replace if higher primary or secondary resistance.

[dsphil]

I had the same problem before. I replaced the coil as well, but didn't help. The last thing I did was giggle the harness around trying to reinstall the ecu. after that, I haven't had this issue since. the second last thing I did was the main relay but that didn't solve the problem. So I think the harness might be bad. I electrical taped the harness like mad so it won't move. So give that a try. good luck.

[Scallywagon]

Fuel lines clogged up?
In-line filter/pump deleted?
How's power reading to your pump?
What does the multimeter say at the DME pins?

[Holland]

Check your AFM. I've been having similar symptoms on my M10. Entire fuel system is new, and now I believe I have tracked the problem to a malfunctioning AFM.

[LateFan]

Fuel lines mostly new - just the few by the in-line pump to do.

New filter. In-line pump was intermittently noisy, likely working too hard due to in-tank pump failure. May change it soon as well to be safe.

Have not checked power to pump yet, nor fussed with DME. (Maybe I'm avoiding DME issues..)

Early on, we checked for free movement at AFM, but now I've read about the track causing problems, so we'd better recheck that.

Thanks -

[603Racing]

You may save yourself time/money by checking fuel pressure. The gauges are usually very cheap or free to rent.

[LateFan]

Bump for update and some more questions.

As we said earlier, we have a new lift pump installed. We put a fuel pressure gauge on the driver's side shock tower. It reads about 39 psi when jumping the relay to run the pumps. Same psi at start-up. It held pressure for several weeks, say 35 psi for a week or two, then slowly dropped off.

The fuel pressure regulator was a working used one from a r3v member. I assume it's good.

We replaced the main, fuel pressure, and o2 sensor relays with new.

I pulled the AFM to clean and test. As part of that process I learned about member Gregs///M and his rebuilding service, and the very limited testing you can do with a DMM. We did check the temp sensor and got normal resistance readings.

The AFM flap is quiet and smooth. (Should we hear the wiper arm dragging on the track at all?)

So - tonight we put it back together and it started right up in a cold (20 degree) garage. Some stumbling from being cold and not running for several weeks, but it warmed right up. No idle cycling, smooth idle, starting at 900 rpm. Fuel pressure about 36.

Temp gauge straight up normal.

Idle began to climb steadily, eventually hitting 1200 to 1300. We ran it for a good 15 minutes or more, looking for vac leaks etc. Fuel pressure about 31 to 32.

After a long time, the idle began to cycle (ICV should probably just go). When the idle drops, it seems more like the engine is shutting off, then catches itself and surges up again. The mileage gauge on the dash shoots across like the engine is off, then catches.

Since we figure the ICV needs to be replaced anyway, what the hell, let's fiddle with the adjustment screw! I turned up to 2 turns out, and the cycling became faster. From zero, I went 2 turns in, and the cycling stopped. Idle still at 1200. Interesting - what does that mean?

At about 20 minutes, it just shut off. It's like turning the key off, no stumble or anything, it just shuts off. Wouldn't restart. Fuel pressure stayed at 36-ish. I wasn't watching it when it died.

I also have some AFM questions - the seal / plug on the adjustment screw is gone. Does it seem likely that someone has been messing with it, trying to make it idle correctly? I checked the tension on the screw and it's loose - no resistance at all. I turned it a couple of turns while idling with no change. Set it back where it was.

Thanks for your patience - is this simple and I'm not doing something basic?

[LateFan]

Went ahead and ordered a new ICV. It passed all tests but it's obviously not working right.

[bddog]

ICV. They are a little spendy , just keep the carburetor cleaner away from them. Tends to melt the insides. You can buy rebuilt AFM most anywhere these days. The penny goes next to the ICV on the intake side.
This car has been sitting this long waiting on a penny?

[LateFan]

I found a new VDO for $177. Rebuilts are about $150, so...

I'm confused by that, because the first thing everyone says is spray it with carb or contact cleaner, clean out the gunk, get it to rattle, yada yada.....

We were making good progress until school and homework and HS soccer changed everything. He doesn't want me to work on it without him so things have slowed. And now the garage is pretty damn cold! We'll rig up a heater and work on weekends when we can.

Suspension next - I want it to run perfectly first.